VNAV in the Cl 650

[arrowspace90]

I know how to fly in LNAV and VNAV, and did it for many years in the 737.  

I thought I would try out the Hotstart 650 for something new to fly.  I found it way more tedious to set up, but after a couple of weeks and learning some strange tricks and things about the very different ATS system, I am able to get it off the ground and up on the route.

But getting it to fly a VNAV path?  Not so easy.  It starts down in VNAV ok at the TOD with the lowest altitude on the STAR set in the window.  And all the crossing restrictions are in the box with no discos.   On an arrival to KSJC with multiple, closely spaced step downs, the 650 made about the first 2 or 3 altitudes.  Then, still at FL200, it leveled out and attempted no more.  Twice I have tried it with that result.  I'm unable to figure out what's limiting it?  All the lower stuff clearly shows on the legs page.

Chagrined, I flew the exact same route in the Zibo 737.  No problems, it made EVERY restriction to G/S intercept and an easy approach.   What feature on the 650 doesn't allow this?  When it stops the descent (which shouldn't be interrupted) I am scrambling to use V/S or FLC to keep it coming down.  Surely this isn't how the real airplane works?

[Pils]

Is it possible to provide screenshots or a video from prior to and during the descent, please? That'd help us figure out what's happening.

Just a clarifying note on some differences between the 737 and Challenger:

1. VNAV isn't a descent mode unto itself, rather it's a modifier on the other modes, e.g. FLC, V/S, PATH, and PTCH. Enabling VNAV will allow the FMS to control altitude preselection to meet flight plan restrictions, and also speeds if separately enabled.

2. The descent path calculated by the FMS is not an idle power descent as is often used in airliners. The Challenger will fly a geometric path, based on the default descent angle set, a per-leg override, or what's required to meet a restriction.

[Prefect99]

17 hours ago, arrowspace90 said:

I know how to fly in LNAV and VNAV, and did it for many years in the 737.

You’re going to have to learn almost from scratch. It’s a very different machine and the initial learning curve is steep. Dig into the included docs as an initial primer, for the first hour or two I simply did cockpit and systems famil on the ground. Using the study menus is really useful and will help you appreciate the detail that has gone into the aircraft.

Then there are some good videos on YouTube from Graeme and Rob Hammer, Toto also makes an appearance from time to time.

Honestly, start slow, treat it like a real type rating. There is also a discord channel too.

Edited January 1 by Prefect99

[arrowspace90]

20 hours ago, Pils said:

Is it possible to provide screenshots or a video from prior to and during the descent, please? That'd help us figure out what's happening.

Just a clarifying note on some differences between the 737 and Challenger:

1. VNAV isn't a descent mode unto itself, rather it's a modifier on the other modes, e.g. FLC, V/S, PATH, and PTCH. Enabling VNAV will allow the FMS to control altitude preselection to meet flight plan restrictions, and also speeds if separately enabled.

2. The descent path calculated by the FMS is not an idle power descent as is often used in airliners. The Challenger will fly a geometric path, based on the default descent angle set, a per-leg override, or what's required to meet a restriction.

Ok, so does that mean that I need to arm a descent mode In Addition to VNAV for the descent?  What additionally is required if the aircraft levels off when it shouldn't?  

Yes, this airplane is really strange compared to other aircraft I have flown.  What can cause the VNAV path to be interrupted after making only 2 of the approximately 10 altitude crossing restrictions?? 

Yes I am taking some phone photos trying this again today as, after tying this route twice, it has leveled at the same spot on the VNAV descent.  If I have to have more than one descent mode selected however, this would explain my problems.  Ha, why would they do that?  The 737 does all this for you in VNAV, why complicate it? 

[arrowspace90]

Well just to embarrass me, the 650 flew a perfect VNAV descent and then a low overcast ILS.  Ha, I was going to send it to the scrap yard! 
I appreciate the comments which were obviously trying to help!

[Pils]

2 hours ago, arrowspace90 said:

Yes, this airplane is really strange compared to other aircraft I have flown.  What can cause the VNAV path to be interrupted after making only 2 of the approximately 10 altitude crossing restrictions??

I can't answer this question without more information. You'd need to provide a video and the full flight plan. It will level off after altitude constraints have been met until it needs to descend again at the default descent angle to meet the next constraint. Maybe that's what you're seeing?

2 hours ago, arrowspace90 said:

Yes I am taking some phone photos

Please take actual screenshots, or better yet a video screen capture (with OBS Studio or similar), of the whole screen. X-Plane even has this ability built-in to take screenshots (don't use it for video), see the keyboard assignments window.

[Pils]

3 hours ago, arrowspace90 said:

Ok, so does that mean that I need to arm a descent mode In Addition to VNAV for the descent?

If there is an "AT"/"AT or ABOVE" constraint on the descent and VNAV is active (annunciated as VALT when at cruise level) then it'll automatically arm the PATH vertical mode (VPATH), which as explained follows a default 3 degree angle to meet the first constraint.